It is generally known to cool a piston by directing a flow of lubricating oil against the underside of the piston crown. More specifically, the prior art typically provides a nozzle or the like in the crankcase area below the piston. The nozzle is aimed so as to direct a flow of oil upward and against the underside of the piston crown. A problem with this arrangement is that the oil flow or stream passing from the nozzle to the piston passes through a very turbulent space due to the rotation of the crankshaft including its balancing weights and the movement of the connecting rods and attached piston. Consequently, the stream of oil is only marginally effective to cool the piston when the piston is near its bottom dead position or closest to the crankshaft. At other piston locations, the oil stream is easily deflected by the aforesaid turbulence.
The subject application provides apparatus for cooling a piston utilizing a reservoir forming pocket between the piston and cylinder wall to which oil is discharged from an aperture in the cylinder wall while the piston moves toward and away from its bottom dead position. Pressurized oil is pumped into the pocket reservoir and the oil is then discharged therefrom through a passageway in the piston which is aimed at the undersurface of the piston crown.
Also, a new method of piston cooling is disclosed including: forming a reservoir space between the side wall of the piston and the engine's cylinder wall; introducing oil into the reservoir space during a portion of the piston movement; providing a passageway in the piston extending from the reservoir space and aimed to direct a stream of oil against the undersurface of the piston.
Other features, objects, and advantages of the invention will become more apparent as the following description proceeds, especially when considered with the accompanying drawings and claims.